<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="">
    <meta name="author" content="">
    <title>Please sign in</title>
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
    <link href="https://getbootstrap.com/docs/4.0/examples/signin/signin.css" rel="stylesheet" crossorigin="anonymous"/>
</head>
    <body>
        <div class="container">
            <form class="form-signin" method="POST" action="/login/login">
                <h2 class="form-signin-heading">Please sign in</h2>
                <p>
                    <label for="username" class="sr-only">Username</label>
                    <input type="text" id="username" name="username" class="form-control" placeholder="Username" required autofocus>
                </p>
                <p>
                    <label for="password" class="sr-only">Password</label>
                    <input type="password" id="password" name="password" class="form-control" placeholder="Password" required>
                </p>

                <div class="online"><input name="imageCode" placeholder="请输入验证码"/>
                    <img src="/valid/code" id="imageCode" alt="验证码" onclick="this.src=this.src+'?'">
                    <a href="javascript:imageCode.onclick()">换一张</a>
                </div>
                <button class="btn btn-lg btn-primary btn-block" type="submit">Sign in</button>
            </form>
        </div>
    </body>
</html>